Package handling apparatus detecting package height

ABSTRACT

An apparatus to test integrity of a seal of a package. The apparatus includes a height detector detecting a height of the package, a test portion determining the integrity of the seal based upon a position of the test portion as a function of time when contacting the package, and a mover moving the test portion into an initial position of contact with the package based upon the detected height. The test portion includes a test head contacting the package, and the mover includes a servo motor driving the test head, and a ball screw linking the servo motor and the test head.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to UK Application No. 0116266.8, filedJul. 3, 2001 and UK Application No. 0126677.4, filed Nov. 6, 2001, thedisclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a package handling apparatus,particularly to an apparatus to test the seal quality of gas-filledpackages and to prepare the packages for such testing.

2. Description of the Related Art

Many types of apparatus to test the integrity of gas-filled packages,such as flexible pillow type bags filled with chips or other snackfoods, have been proposed. Generally, a test head is lowered onto apackage to apply a load which will cause a leaky package to deflate. Toachieve a measurable effect in a short time, large loads must be applied(e.g. 2.5 kg), with considerable risk of damage to the contents of thepackage. This system has a high inertia and is therefore slow,inaccurate and inconsistent. Furthermore, this system is difficult toadjust, e.g., for adapting to different package types. Thus, after eachtest, the head is raised to a maximum height, wasting much time.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide anapparatus which is faster, more efficient, and more adaptable thangeneral designs.

Additional objects and advantages of the invention will be set forth inpart in the description which follows and, in part, will be obvious fromthe description, or may be learned by practice of the invention.

The foregoing and other objects of the invention are achieved byproviding an apparatus to test integrity of a seal of a package. Theapparatus includes a height detector detecting a height of the package,a test portion determining the integrity of the seal based upon aposition of the test portion as a function of time when contacting thepackage, and a mover moving the test portion into an initial position ofcontact with the package based upon the detected height. The testportion includes a test head contacting the package, and the moverincludes a servo motor driving the test head, and a ball screw linkingthe servo motor and the test head.

The foregoing and other objects of the invention are also achieved byproviding an apparatus to test integrity of a seal of a package,including height detecting means for detecting a height of the package;determining means for determining the integrity of the seal based upon aposition of the determining means when contacting the package; andmoving means for moving the determining means into an initial positionof contact with the package based upon the detected height.

The foregoing and other objects of the invention are also achieved byproviding an apparatus to test integrity of a seal of a flexiblegas-filled package having a pillow shape, including a conveyor conveyingthe package through the apparatus; a height detector detecting a heightof the package; a test portion determining the integrity of the sealbased upon a position of the test portion as a function of time whencontacting the package; and a mover moving the test portion into aninitial position of contact with the package at a height above theconveyor which is based upon the detected height of the package.

The foregoing and other objects of the invention are also achieved byproviding a method to test integrity of a seal of a package, includingdetecting a height of the package; contacting the package with a testingdevice, including moving the testing device to contact the package at aninitial position of contact determined by the detected height; anddetermining the integrity of the seal based upon a position of thetesting device as a function of time when contacting the package.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe preferred embodiments, taken in conjunction with the accompanyingdrawings of which:

FIG. 1 is a schematic side elevational view of an apparatus according toan embodiment of the present invention;

FIGS. 2A and 2B are plan and side elevation views, respectively, of aroller array of the conditioning section of FIG. 1;

FIG. 3 is a front elevational view of a light curtain device to gaugepackage height of FIG. 1;

FIGS. 4A and 4B are plan and side elevational views, respectively, ofthe testing station of FIG. 1;

FIGS. 5A and 5B are enlarged plan and side elevational views,respectively, of the actuator assembly of the testing station of FIGS.4A and 4B;

FIG. 6 is a schematic graph showing test results; and

FIG. 7 is a side elevational view showing the testing station of FIG. 1downstream of a package sensing apparatus, according to an additionalembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferredembodiments of the present invention, examples of which are illustratedin the accompanying drawings, wherein like reference numerals refer tolike elements throughout.

FIG. 1 shows part of a production line to receive packages 40 (see FIG.3) from a package filling and sealing apparatus, and to test thepackages 40 prior to placement in trays or cartons. As an example, thepackages 40 may be flexible pillow type bags filled with articles suchas chips or other snack foods. Generally, between the package fillingand sealing apparatus (which may be off-line) and the illustratedapparatus, there are one or more intermediate stations, e.g., to orientthe packages 40.

The packages 40 are carried on a conveyor belt 10 or other conveyingunit having a direction of displacement as shown by the arrow 12. In theembodiment shown in FIG. 1, this conveying direction slopes gentlyupwards.

The packages 40 are conveyed to a conditioning station 14. Here, thearticles are agitated by passage over a rumbling conveyor 16 while beingpressed gently from above by an overhead conveyor 18, with a lower runbeing pressed down by a pressing element 20, having, for example, acatenary shape.

The arrangement of the overhead conveyor 18 and pressing element 20 maybe generally as described in application WO 95/32123 to Bennett. Thisapplication discloses the use of a rumbling conveyor, in the form of aconveyor belt having two square-section rollers in contact with theunderside of the conveyor belt. Upon rotation, the corners of the squaresection rollers cause the conveyor belt to repeatedly rise and fall in aflapping motion. Although not illustrated herein, this is onearrangement that may be used.

The arrangement of the overhead conveyor 18 and the pressing element 20may also be as shown in FIGS. 1, 2A and 2B. FIGS. 2A and 2B show aseries of tapered rollers 22 having horizontal axes of rotation,alternate rollers 22 tapering on opposite ends but being rotated in thesame direction to move the package along while being jolted. Thisprovides a thorough but gentle shaking. Furthermore, the gaps betweenthe rollers 22 allow debris (e.g., chips from broken packages) to fallthrough, preventing the debris from passing to the next station.

Downstream of the conditioning station 14 is a testing station 30. Thepackages 40 are conveyed through the testing station 30 on the conveyorbelt 10. Before entering the testing station 30, the packages 40 passthrough a curtain of light, extending between an emitting array 32, anda photocell array 34, arranged at respective sides of the conveyor belt10, as shown in FIG. 3. Light, for example, laser light, is conveyed toa vertical line of emission points in the emitting array 32 along aseries of fiber optic cables 36, and the individual photocells thereto.Other light transmitting devices may also be used in place of the fiberoptical cable 36. As shown in FIG. 3, a package 40 partially occludesthe light curtain. The outputs of the photocells are fed along a cable12 to a remote control unit (RCU) employing a computer 43, or other dataprocessing device (FIG. 1), which uses the output data to identify amaximum height of the package 40. As illustrated herein, the package 40is generally pillow-shaped after conditioning, with the upper surface ofthe package 40 being supported primarily by the cushion of gas (air)within the package 40, rather than by contact with the solid articles.Although pillow-shaped packages are described herein, the presentapparatus may be used to test gas-filled packages of any shape.

Since the speed of the conveyor belt 10 is known, the passage of thepackage 40 through the light curtain can also be used to measure thelength of the package 40. These measurements can be used to identify thetype of package 40 from a range of the packages 40 that differ indimensions, and whose data have been fed into the computer 43.

The testing station 30 includes a test head 50 (FIG. 4B), and unit tocontrollably move the test head 50 towards and away from the conveyorbelt 10. The test head 50 is shown as having an array of nonback-pressure rollers 53 which extend transversely across the conveyorbelt 10 and define a main contact surface portion 54. This contactsurface portion 54 is parallel with the surface of the conveyor belt 10,bending upwardly at the upstream side to define an angled lead-insurface 56. It is also possible to use a belt driven in synch with theconveyor belt 10.

The test head 50 further includes a body 52, which is mounted to twopairs of levers 58, 60 at each lateral side of the body 52. The lowerends of the lower limbs of corresponding levers 58, 60 are linked byshafts 62. Although the levers 58, 60 generally have an L-shape in FIG.4A, other shapes are also possible.

The testing station 30 further includes a fixed body 70. The levers 58,60 are mounted to the fixed body 70 by pivot shafts 72, which connectcorresponding levers 58, 60 at the intersection of their limbs. Thus,the test head 50 is carried by parallelogram linkages, so that it moveswith its main contact surface portion 54 maintained parallel with thesurface of the conveyor 10. At each side of the testing station 30, theupper limbs of the two levers 58, 60 are linked to a respectivelongitudinally extending shaft 74 (FIG. 4A). The shafts 74 are linked bya transverse rod 76 which passes through a displaceable piston sleeve78. The piston sleeve 78 is constrained by the parallelogram linkages tomove approximately horizontally (actually, through an arc), and themovement thereof causes pivoting of the levers 58, 60, with concomitantrising or falling of the test head 50.

The piston sleeve 78 is linked to a motor, for example, a servo motor80, via, for example, a ball screw coupling. This employs ahigh-resolution load-matched ball screw for maximum sensitivity andreduced backlash. Furthermore, the test head 50 is biased for zerobacklash measurements.

The servo motor 80 can be operated in torque control mode, so that anaccurately known force is applied downward to the test head 50. This ismade possible by the simple and direct mechanical coupling between theservo motor 80 and the test head 50 (via the ball screw and the leverarms). The motor 80 is pivotally mounted to the fixed body 70 throughstub shafts and pivots slightly to allow the arcuate movement of thepiston sleeve 78.

FIGS. 5A and 5B are enlarged views of the servo motor 80, the pistonsleeve 78, and the actuation therebetween.

In normal use, the arrival of the package 40 to be tested is detected bythe light curtain device, providing data indicating the height of thepackage 40. This information is used to control the servo motor 80, sothat the test head 50 is raised sufficiently to allow the package 40 topass beneath. The test head 50 does not need to be raised to the maximumheight each time. A further possibility is for the heights of amultiplicity of packages 40 to be recorded, and for the computer 43 todetermine an expected package height range or “tolerance band”. This canbe used to provide a standard height to which the test head 50 israised, and/or to cause rejection of packages 40 which are outside thetolerance band. This could, for example, prevent the test head 50 frombeing lowered onto debris such as escaped chips which had reached thetesting station 30.

When the light curtain has determined that a proper package 40 haspassed, the computer 43 can determine precisely when the package 40 willbe beneath the test head 50, since the computer 43 also receives dataabout the speed of the conveyor belt 10. The test head 50 is thereforelowered by actuation of the servo motor 80, in a controlled fashion,with controlled torque. The height of the test head 50 is monitored,generally by monitoring the operation of the servo motor 80. FIG. 6 is aschematic graph showing the height (h) of the test head 50, versusdistance (s) traveled by the package 40. Initially, when the test head50 contacts a balloon-like article, there is a tendency to sink down andrise up again, giving a dip region 81. Furthermore, oscillations aredamped by the servo motor 80. For a non-leaking package 40, the dip isfollowed by a horizontal region 82, as the test head 50 applies aconstant torque and is supported at a constant height. However, if thepackage 40 leaks, the test head 50 will descend, leading to the downwardgradient of broken line 84. A leaky package 40 can be detected by notingand comparing the values of the height parameter at two spaced intervalsA and B. The test assembly can also be used in a positional speed mode.

To determine the appropriate test torque, a destruction test may becarried out on a package 40 as follows. After conditioning, the package40 is placed beneath the test head 50, with the conveyor belt 10stationary. The servo motor 80 is then operated to cause the test head50 to descend, until the package 40 bursts. The pressure (or torque) atwhich the bursting happens is noted, and a fraction of this pressure(e.g., 40%) is then used as the standard applied value for testingsimilar packages 40.

The test head 50 measures both torque and height, which can be doneusing the servo motor 80. It is also possible to include a load cell tomeasure torque/pressure values.

The seal test apparatus of the present invention can handle packages 40very gently, reducing the risk of bursting or scratching. Typically, theload applied is 1.5 kg or less, but greater loads may also be applied.The extremely sensitive height sensing (due to the direct linkage to theservo motor 80 via the ball screw) enables even tiny leaks to bedetected, at high travel speeds. An output of 150 packages 40 per minuteor more can be achieved.

A conventional apparatus must be mechanically reset each time theproduct changes or if any parameter is varied. With the presentapparatus, changes in height are automatically accounted for by theemitting array 32 and the photocell array 34. If necessary,recalibration of the head 50 is simple, as described above.Specifically, no mechanical alteration is required since the computer 43controls the torque to be applied by the servo motor 80. The ability tovary the test load to match the type or product provides the ‘best-fit’compromise between maximum accuracy of leakage measurement and productfragility. Depending on the application, the user can select betweenusing the maximum possible pressure to detect the smallest leaks or theminimum pressure to minimize product damage or burst packages 40.

The test head 50 is kept in contact with the package 40 only during thetest period, thereby minimizing the risk of product jams. The defaultdirection of movement for the test head 50 is upwards, away from thepackage 40, leaving pathways clear except during power up/down phases.

Stability of test head geometry is crucial due to the fine measurementtolerances required, especially with short contact periods at highspeed. Sanitation procedures may require the test head 50 to be removedand replaced occasionally. This can be done precisely without the needfor re-calibration. Problems with product debris affecting or causingvariations in the home point are eliminated. There is no need to clearproduct from the machine during start-up as with previous designs.Parameters can be altered ‘on-the-fly’ and will take immediate effectwithout the need to stop the machine.

The treatment of ‘gross leakers’, below minimum height packages 40 andabove maximum height packages 40 can be handled individually to suitcustomer requirements and plant layout. Air divert direction, delay andduration can be individually selected on the remote console of the RCU.

The conveyor belt 10 is accurately controlled to maximize measurementstability and repeatability. Speed can be reduced for longer testperiods as typically required for larger packages 40. Speed can beprofiled to maximize test times at higher speeds for greater accuracy.

The feedback from the test-head 50 needs to match as closely as possiblethe height and hence the deflation curve of the product as it passesunderneath. Servo feedback or non-contact height measurement may be usedto provide an accurate (approximately 1 μm), linear reading.

FIG. 7 shows a test section 30′ according to a second embodiment of thepresent invention, having an associated sensing apparatus 90. The testsection 30′ may be essentially the same as the test section 30 alreadydescribed, with a test head 50′ mounted on L-shaped levers 58′, 60′movable by a servomotor 80′. The sensing apparatus 90 may take the placeof the light curtain device 32, 34, and includes a device to contact thepackages 40, such as a pivotable endless belt 92 (shown in severalangular positions) extending in the package conveying direction (seearrow A). Other contact devices are also possible. The belt 92 ispivotally mounted by a transverse pivot 94 at an upstream or drive side(relative to the package conveying direction A). The belt 92 is drivenby a motor 96 or other drive unit, via a linking mechanism such as adrive belt 98. A measuring device, for example, an encoder 100 (in thisexample a 2000 per rev encoder) measures the angle of the belt 92.

The belt 92 is lightly biased in a counter-clockwise direction so thatthe free downstream end is close to or in contact with the upper surfaceof the conveyor belt 10. The package 40 moved by the conveyor 10 entersthe nip defined between the conveyor 10 and the pivotable belt 92, andcontacts the belt 92, whose surface is moving at substantally the samespeed as the conveyor. The contact causes the belt 92 to pivot clockwisesufficiently to allow the package to pass beneath. In the process, thepackage 40 may undergo some stabilization of its contents. The amount ofpivoting is measured by the encoder 100. This provides data to controlthe servo motor 80 of the test section 30′ to position the test head 50′appropriately.

This device enables package 40 to be fed into the test section 30′smoothly. The test head 50′ is positioned to the correct height for eachpackage 40 by feedback from the encoder 100. This allows a much morecontrolled application of the test head 50′ force onto the package 40.Feedback is consistent because the package 40 will be stabilized to someextent by the pivotable belt 92. The belt assembly has been designed tobe as light as possible to prevent seal damage or popping of packages 40caused by the inertia of the present heads.

The light curtain device is described as including fiber optic cables,laser light, and photocells. However, the present invention is notlimited to any particular type of radiation, emitter or detector. Thesensing apparatus 90 is described as including endless belt 92, motor96, drive belt 98, and encoder 100. However, the present invention isnot limited to any particular type of contact surface, drive source,force transfer device, or measurement device. The testing station 30 isdescribed as including levers 58, 60 and rollers 53, however, thepresent invention is not limited to any particular type of movingdevice. The present description also includes a servo motor 80, and aball screw, however, the present invention is not limited to anyparticular type of drive source or force transferring device.

Although a few preferred embodiments of the present invention have beenshown and described, it will be appreciated by those skilled in the artthat changes may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. An apparatus to test integrity of a seal of a package, comprising:height detecting means for detecting a height of the package; movingmeans for moving a contact member to a height greater than the height ofthe package and to an initial position of contact with the package basedupon the detected height; and determining means for determining theintegrity of the seal based upon a change in position of the contactmember from the initial position of contact over time, wherein theheight detecting means comprises: a contact surface contacting thepackage and pivoting as a result of the contacting, and a pivot detectordetecting a degree of the pivoting and determining the height of thepackage therefrom.
 2. An apparatus to test integrity of a seal of apackage, comprising: a height detector detecting a height of thepackage; a mover moving a contact member to a height greater than theheight of the package and to an initial position of contact with thepackage based upon the detected height; a test portion determining theintegrity of the seal based upon a change in position of the contactmember from the initial position of contact over time, wherein theheight detector comprises: a contact surface contacting the package andpivoting as a result of the contacting, and a pivot detector detecting adegree of the pivoting and determining the height of the packagetherefrom.
 3. The apparatus of claim 2, wherein the contact membercomprises a test head, and the mover comprises: a servo motor drivingthe test head; and a ball screw linking the servo motor and the testhead.
 4. The apparatus of claim 3, wherein the test portion determinesthe integrity of the seal based upon a force applied by the servo motoron the test head.
 5. The apparatus of claim 3, further comprising aconveyor conveying the package through the apparatus.
 6. The apparatusof claim 2, wherein the contact surface is an endless belt.
 7. Theapparatus of claim 2, wherein the pivot detector is an encoder.
 8. Theapparatus of claim 3, wherein the ball screw is a high-resolutionload-matched ball screw.
 9. An apparatus to test integrity of a seal ofa flexible gas-filled package having a pillow shape, comprising: aconveyor conveying the package; a height detector detecting a height ofthe conveyed package; a mover moving a contact member to a heightgreater than the height of the package and to an initial position ofcontact with the package at a height above the conveyor which is basedupon the detected height of the package; a test portion determining theintegrity of the seal based upon a change in position of the contactmember from the initial position over time, wherein the height detectorcomprises: a contact surface contacting the package and pivoting as aresult of the contacting, and a pivot detector detecting a degree of thepivoting and determining the height of the package therefrom.
 10. Theapparatus of claim 9, wherein: the apparatus tests the integrity of theseals of a plurality of the packages, the conveyor conveys a next one ofthe plurality of the packages to the height detector, the heightdetector detects a height of the next one of the packages, and the movermoves the contact member to an initial position of contact with the nextone of the packages at a height above the conveyor which is based uponthe detected height of the next one of the packages.
 11. A method totest integrity of a seal of a package, comprising: detecting a height ofthe package; moving a contact member to a height greater than the heightof the package and to an initial position of contact with the packagedetermined by the detected height; determining the integrity of the sealbased upon a change in position of the contact member from the initialposition as a function of time, wherein the detecting of the heightcomprises: contacting the package with a pivot portion, pivoting thepivot portion as a result of the contact with the package, detecting adegree of the pivoting of the pivot portion, and determining the heightof the package from the detected degree of pivoting.
 12. The method ofclaim 11, further comprising: placing a test package under the contactmember; applying an increasing load to the test package with the contactmember until the test package bursts; and applying a load to subsequentones of the packages that is a fraction of the load applied to the testpackage.
 13. A method to test integrity of a seal of a package,comprising: detecting a height of the package; setting an initialposition of contact between a contact, member and the package dependingon a type of the package, so as to avoid an extra movement of thecontact member based on a detecting speed; and moving the contact memberat the initial position of contact and determining the integrity of theseal based upon a change in the position of the contact member from theinitial position as a function of time, wherein the detecting of theheight comprises: contacting the package with a pivot portion, pivotingthe pivot portion as a result of the contact with the package, detectinga degree of the pivoting of the pivot portion, and determining theheight of the package from the detected degree of pivoting.
 14. Anapparatus to test integrity of a seal of a package, comprising: heightdetecting means for detecting a height of the package; moving means formoving a contact member to an initial position having a height greaterthan the height of the package; and determining means for determiningthe integrity of the seal based upon a change in position of the contactmember from the position of contact over time, wherein the heightdetecting means comprises: a contact surface contacting the package andpivoting as a result of the contacting, and a pivot detector detecting adecree of the pivoting and determining the height of the packagetherefrom.
 15. An apparatus to sense a height of packages, comprising: aconveyor to convey the packages; a contact element to be pivoted by theconveyed packages, the contact element comprising: a first end, and asecond end downstream from the first end in a direction of conveyance ofthe packages and closer to the conveyor than the first end; and a sensorto determine an amount of the pivoting of the contact element to therebydetermine a height of the packages.